Brake



22, .1936. R, vs SANFORD 2,055,241

BRAKE Filed Feb. 8,V 1932 2 Sheets-Sheet l 7b/lnN/Fow .33 35 l/ :l 72REAR 35- l BRAKES LJ5 40 O 62 556 Z e az 6 v Z5. 6

4+ 50 F/ gJ 26 26 Q O 4 Z0 O A TT NEY Sept. 22, 1936. R. s. SANFORD2,055,241-

BRAKE Filed Feb. 8, 1932 2 Sheets-Sheet 2 IN VEN TOR.

ROY 5. SANFoRn BY 11 ATTORNEY Patented Sept. 22, 1936 UNITED STATESPATENT OFFICE BRAKE Application February 8, 1932. Serial No. 591,722

3 Claims.

This invention relates to a brake mechanism for automotive vehicles, andparticularly to power operated means for supplementing a brake operatingstructure of the torque equalizing type.

With such an equalizing structure, mechanism is provided that operateswhen the friction is equal in the different brakes to thrust the brakefriction elements against the brake drum with the same degree ofpressure and that also operates when the friction tends to be unequal toeffect as much greater pressure on the friction elements exacting thelesser friction and as much less pressure on the friction elementsexerting the greater friction as will substantially equalize l5 thefriction in the different brakes, so that the braking action of thetires upon the road will be as nearly alike as possible.

It is apparent that in order to obtain adequate braking that asubstantial amount of pressure upon the pedal must necessarily beexerted when the coeiicient of friction of one of the brakes ismaterially lowered; for example, when the lin' ing becomes wet or oily.I

It is, therefore, the principal object of the invention to provide abooster or power mechanism adapted for use with a torque equalizedbraking system to thereby supplement the manual effort of applying thebrakes.

Other objects of the invention and desirable details of construction andcombinations of parts will become apparent from the followingdescription of a preferred embodiment taken in conjunction with theaccompanying drawings, in which:

Figure 1 is a diagrammatic view of the braking mechanism constitutingthe present invention;

Figure 2 is a sectional view of the booster motor;

Figure 3 is a sectional view of the control valve for the booster motor;

Figure 4 is a sectional view taken on line 4 4 of Figure 1 disclosingthe cam operating structure of one of the wheel brakes; and

Figure 5 is a diagrammatic view on a small scale illustrating inaddition the connection to the rear brakes.

In that embodiment of the invention selected for illustration there areprovided front wheel brakes l0 and I2 of the internal expanding type.Each brake preferably comprises a pair of adjustably connected oatingfriction lined shoes I4 and l5, one or the other of which, dependingupon the direction of wheel rotation, is adapted to anchor on a cammember it rotatably mount- (Cl. 18S-152) w` ed on a xed anchor 20secured to a support plate 22. Each of the brake structures includes theusual rotatable brake drum 24 to be contacted by the brake shoes. Thecam I8 is provided with an integrally connected actuating arm 26 oper- 5ably connected at its end to a flexible cable member 28 housed within aflexible sheath or conduit 30 secured at one of its ends to the supportplate 22. The conduit at its remaining end may be secured by a tting 32to the chassis of the i0 vehicle.

The cables of each brake are connected at 34 with a common actuatingcable 36, the latter being pivotally connected to the end of the lower parm of-a foot pedal lever 38 accessible to the l5 driver. One of thecables 28 also passes over fixed pulley 35 in order to keep theconnection 34 normally substantially one-half way between the guidedportions of the cables 28. The rear brakes of the vehicle are preferablyapplied by I rod 40, pivotally connected to the pedal above its pivotalmounting or fulcrum 42.

Describing the operation of the aforementioned brake structure,actuation of the pedal 38 serves to rotate the cams i8 to spread theshoes apart g5 and apply the brakes. It will be seen that if the degreeof friction between the brake shoes and brake drum is greater in one ofthe brakes than in the remaining brake that the tendency to rotation ofthe brake shoes in the brake having the 30 greater friction will begreater than that of the brake shoes in the brake having the lesserfriction and, consequently, that brak'e having the greater friction-will retract its associated cam actuating arm 26 suiiiciently to exerta pull on 35 the adjacent end of its cable 28 in a direction opposite toand counteracting the pull on the cam lever of the remaining brakeproduced by presu sure of the operators foot upon the brake pedal. Thusas much greater pressure will be effected 4o on the brake shoes exertingthe lesser friction and as much less pressure will be effected on theshoes exerting the greater friction as will sub;- stantially equalizethe friction between the different drums and their associated brakeshoes. y

This means that thevtorque or braking eiect of one of the front brakesis equal to that of the remaining front brake, and it follows that asubstantial amount of foot pressure must be applied to the pedal leverto obtain effective braking of the front brakes when at least one ofsaid brakes is inefficient.

In order to compensate for this additional burden upon the driver. powermeans are provided to supplement his eort.

To this end there is provided a uid motor 44 comprising a casing 46,pivotally secured to the chassis by link 48, and a reciprocable piston50, pivotally secured by a rod 52, to the pedal 38. The rod 52 ispreferably connected to the pedal below .the connection with the rearbrakes. The cylinder 46 is adapted to be evacuated of its air, or asubstantial portion thereof, to thereby impose an atmospheric load uponthe piston 50 to apply the brakes and thereby augment the physicaleffort of the driver, all as previously described. To this end thecylinder 46 is connected with the intake manifold of the internalcombustion engine, not shown, via conduits 54 and 56, a control valvefor the motor being interposed in the conduit circuit. The valve, whichforms no part of the instant invention, briefly comprises two relativelymovable casing and diaphragm parts 58 and 60 connected respectively, tothe chassis and to the pedal, by links 62 and 64. A spring 66 isinterposed in the connection between the diaphragm and pedal to obviateinjury to the valve parts when the power mechanism is inoperative.

Operation of the valve by the pedal 38 serves to place the manifold incircuit with the cylinder 46 to thereby evacuate the latter and applythe brakes by power. As is Well-known in the art, the manifold at closedthrottle is evacuated to a subatmospheric pressure of approximately tenpounds perffsquare inch. Describing the operation of the brake mechanismin greater detail, counterclockwise movement of the pedal serves tosimultaneously manually apply the front and rear brakes and operate thevalve to apply the brakes by power. It will also be noted that the frontand rear brakes are applied by physical eifort, or at least theapplication of said brakes is initiated, prior to the power operation ofthe brakes; for with the structure disclosed the brakes will be operatedwith the initial movement of the pedal 38. It will further be noted thatwith the particular arrangement of the parts that the power device isincapable of applying the brakes alone and that with release of thepressure upon the pedal the valve is actuated to denergize the fluidmotor and release the brakes. The spring 66 also insures a follow-upaction of the valve, permitting the same to be self-lapping to hold thebrakes as applied.

There is thus provided a very effective brake mechanism insuring equalbraking eillciency of the front wheel brakes and also insuring adequatepedal pressure to render said brakes eiective. In Figure 5 there`isshown diagrammatically the complete arrangement of a hookup in which therear brakes are also operated by the same type of structure, thusproviding a power operated four wheel brake system in which the torqueof the two front wheels is equalized and the torque of the two rearwheels is also equalized.

While one illustrative embodiment has been described, it is not myintention to limit the scope of the invention to that particularembodiment, or otherwise than by the terms of the appended claims.

I claim:

l. An automotive brake structure comprising, in combination, wheelbrakes, means including a manually operable member for so operating thewheel brakes as to obtain an equal braking eect from each of saidbrakes, and power means lncluding relatively movable cylinder and pistonmembers, said piston member being directly connected to said manuallyoperable member, said power means' further including a valve member alsodirectly connected to said manually operable member, said power meanssupplementing the operation of the aforementioned manually operablemember.

2. An automotive brake structure comprising in combination wheel brakes,means including a manually operable member for so-operating the wheelbrakes as to obtain an equal braking effect from each of said brakes,and power operating means connected to and adapted to assist the effortapplied to the first mentioned means.

3. An automotive brake structure for a vehicle having a frame comprisingin combination wheel brakes, means including a manually operable memberfor operating the wheel brakes so as to obtain equal braking eiect fromeach of said brakes and comprising a pivoted foot pedal, a tensionconnection from said pedal to said brakes, an applying member for eachof said brake's which are operated by said connection and on which thetorque from the braking reacts, and equalizing means interposed in saidconnection, power means including a cylinder secured to said frame anda-movable piston in said cylinder, said piston being connected to thepedal directly and non-resiliently, said power means also including avalve member for controlling the cylinder and piston having one portionsecured to the frame and having another portion resiliently connected tothe pedal, said power means supplementing the operation of theaforementioned manually `operable means.

